Research On Characteristics Of An Equipment's Slewing Bearing System In Underwater Pressure Environment

Slewing bearing system underwater which plays an important role in a reliable operation of an underwater equipment is very necessary to be studied in depth. In this paper,a large three-row cylindrical roller slewing bearing underwater is used as the research object. The basic theories and methods of Hertz elastic contact theory and the Palmgren-Lundberg fatigue life theory are applied. Considering the particularity and complexity of the underwater pressure condition, the influence of different structural parameters and load parameters on the slewing bearing load distribution characteristics and fatigue life for both installations of inner ring is studied.For the installation that the inner ring of the slewing bearing is fixed with the outer surface of hollow cylindrical structure, considering the rigid ring assumption, the load distribution model is analyzed when the slewing bearing has a clearance. The expression about limit of the slewing bearing's radial clearance is derived, furthermore how to improve limit radial clearance is proposed. Using iterative method to get the root of the equation by programing in MATLAB, we can know how the load distribution and fatigue life change when radial clearance, radial load, the number of roller, roller diameter and roller bearing length are different.The inner ring shape after deformation due to the difference between internal pressure and external pressure in the underwater environment is an ellipse by using the Least-square fitting. The maximum contact force is at the top of the slewing bearing before deformation, but the maximum contact force is along the line of radial load after deformation, Before and after deformation the bearing load distribution is obviously different. The nonlinear dynamics simulation model of slewing bearing system underwater is established, the simulation results show that the inner ring deformation will cause rotary characteristics to become bad.For the installation that the inner ring of the slewing bearing is mounted on the outer surface of hollow cylindrical structure with interference fit. The gap at the junction caused by internal and external pressure of the hollow cylindrical structure can be compensated by a clearance compensation mechanism, the FEM software COSMOS / simulation analysis shows that proper parameters including the arrangement and the number of clearance compensation mechanisms, the thickness of inner ring can achieve the optimum slewing bearing performance. The results can provide the theoretical direction for design, manufacture, and maintenance of the slewing bearing system underwater, which possess an important throretical significance and application value in engineering.